Process of decomposing lignified fibers



Patented, May 12, 1931 UNITED STATES PATENT oF icE WALTER SEIDEL AND RUDOLF IE INGADO, OF DORMAGEN, GERMANY, ASSIGNORS TO I. G. FARBENINDUSTRIE AKTIENGESELLSCHAFT, IRANKFORT-ON-THE-MAIN,

GERMANY, A CORPORATION OF GERMANY PROCESS OF DECOMPOSING LIGN'IFIED FIBERS No Drawing. Application filed January 21, 1980, Serial m5. 422,481, and in Germany January 25, 1929.

The present invention relates to a process 1 of decomposing lignified fibers, especially wood, according to the'sulfite pulp process.

In the sulfite pulp process the wood, generally in form of chips, is decomposedby an aqueous solution of acid calcium sulfite at temperatures of about 130150, said 7 rocess being described in literature f. e. inArt-ificial Silk byValentin Hottenroth, London 1928 page 48 it. This process however requires a-prolonged time say up to 16 hours.

, Now we have found that the decomposition of wood according to the sulfite pulp process can be achieved in-a highly reduced time without injuring the product thereby by carrying out the process in the presence of oxygen or gases contalning oxygen, which gases are introduced into the digester during the boiling process thus allowing the oxygen to act upon the boiling wood.

The quantity of oxygen introduced may be varied within the widest limits, generally we add about 210% of oxygen calculated on the amount of the wood to be decomposed. The reduction of time achieved-depends on the quantity of oxygen introduced, thus the process requiring only one fourth of the time usually necessary when adding about 10% of oxygen. 'Our invention can be performed in various manners; for example the oxygen can be continuously introduced into the boiler during the whole process, or it can be added interruptedly in portions f. e. after each ten minutes. The oxygen maybe introduced directly into the digester or it may be passed into the sulfite lye when the same is caused to circulate by pumping in a cycle during the boiling process. Before starting with introducing the oxygen, we generally heat the reaction mixture to the decomposition tempera ture, say 130150.'

the digester and heating to the boiling temperature) is necessary.

On the other hand the same process is carprocess is complete after 4 3. The process which comprises heating a mixture of chips of red pine wood and acid calcium sulfite lye to about 130150 and then adding about 10% of oxygen, calculated on the amount of the wood, in small portionsto the reaction mixture in the course of about 4 hours, thereby maintaining the temperature.

In testimony whereof, we aflix our signatures. WALTER SEIDEL.

' RUDOLF F INGADO.

The following example serves to illustrate I our invention, without limiting it thereto Emample.0n one hand 350 kgs. of chips of red pine wood are heated with aqueous acid calcium sulfite lye to 140-150 in the known manner while pumping the lye in a cycle. For finishing the decomposition process 16 hours boiling (i. e. withoutnfilling 

